Franklin climate

Franklin Frost Dates and Growing Season

NOAA 1991-2020 normals for Preston, 10.8 km from Franklin, elevation 4719 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Preston. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around May 16 and the first fall freeze around September 28, a growing season of about 133 days.

Median at 36°F
last June 3, first September 17
Median at 32°F
last May 16, first September 28
Median at 28°F
last April 30, first October 10

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FJun 19Jun 14Jun 10Jun 6Jun 3May 31May 26May 22May 16
32°FJun 4May 28May 24May 20May 16May 13May 9May 6May 2
28°FMay 13May 8May 4May 2Apr 30Apr 27Apr 23Apr 19Apr 13
24°FApr 29Apr 23Apr 20Apr 16Apr 12Apr 7Apr 4Mar 31Mar 24
20°FApr 14Apr 7Apr 2Mar 30Mar 25Mar 19Mar 15Mar 11Mar 6
16°FMar 29Mar 20Mar 15Mar 11Mar 8Mar 5Mar 3Feb 28Feb 24

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FSep 3Sep 8Sep 11Sep 14Sep 17Sep 20Sep 23Sep 26Oct 1
32°FSep 14Sep 19Sep 23Sep 26Sep 28Oct 1Oct 4Oct 7Oct 14
28°FSep 26Oct 1Oct 4Oct 7Oct 10Oct 14Oct 17Oct 21Oct 26
24°FOct 8Oct 15Oct 18Oct 21Oct 24Oct 27Oct 30Nov 3Nov 8
20°FOct 19Oct 25Oct 29Nov 1Nov 3Nov 7Nov 11Nov 15Nov 21
16°FOct 28Nov 2Nov 7Nov 11Nov 14Nov 17Nov 21Nov 24Nov 29

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F12511911210710298948781
32°F156148143138133128124118110
28°F185179173169164160155150142
24°F217209204198195190185180172
20°F248240235230225219214207199
16°F270262257253249244238233223

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
6,994
Cooling degree days, base 65°F
461
Growing degree days, base 40°F
4,253
Growing degree days, base 45°F
3,184
Growing degree days, base 50°F
2,280
Growing degree days, base 55°F
1,535
Growing degree days, base 60°F
926

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27700
February1,03600
March81405
April570037
May3235186
June11154397
July12208662
August18170617
September17523309
October527065
November89102
December1,24000

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 10.8 km from Franklin. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00107346 (Preston). Public domain.